At least, Sarah thought, she wasn’t the only one at the police station in a Dirndl, though hers was the only one with a side seam busted open. She counted a half dozen people in ball costumes, two of them in handcuffs, singing a spirited version of “Das Schönste auf der Welt” at the top of their lungs. The officer who was transcribing Sarah’s statement looked up at the serenaders, frowned, then informed Sarah that the song was a fine one if sung properly, in tune.

Well, she had definitely arrived in Vienna.

There had been quite a scene with the police. After Sarah had explained to the officers what she was doing in the lab and they had holstered their guns, one officer had been dispatched to collect Alessandro from the Platz. By then, Nina Fischer had arrived.

It was Nina who had sent the police to the lab. Bettina Müller, it seemed, had phoned Nina in a panic, saying she had gotten a text from a blocked number telling her that her laboratory had been broken into.

“But she couldn’t come herself,” Nina explained. “Because she was already on a train.”

Sarah, Nina, and Alessandro were all taken to the station to make statements. They filled out form after form, repeating all their information, and signing reports. Neither the Polizei nor Nina was able to reach Bettina Müller, who, by the end of the evening, was under suspicion of having stolen her own laptop from herself..

“Perhaps she is not getting phone reception on the train,” Nina offered, outside the police station.

“Do you know where she lives?” Sarah asked. “I’m sorry. I’m really not a crazy stalker. It’s just that I urgently need to speak with her. She did invite me to the lab tonight. . . .” If she had even sent that message.

“I don’t.” Nina raked her fingers through her pink hair. “Somewhere near the Naschmarkt, I think. She always breakfasts there. Shit. But, look, she should be back by Friday at the latest. That’s when our team always meets. And there is a concert that night, at the Konzerthaus. She never misses when Kapellmeister Schmitt is conducting.”

Sarah headed to the Naschmarkt, feeling melancholy, which wasn’t helped by a drizzle of cold rain. She ordered a Melange, the Austrian equivalent of a latte, and a Topfengolatsche, which was Austrian for “You have gone to pastry heaven. You’re welcome.” Sugar inspired, Sarah wondered if maybe Nina Fischer knew of any similar work to Bettina’s being done somewhere else. Sarah thought she had run down every other avenue when she was in Boston, but maybe . . .

Her phone beeped.

I had to leave. My life is in danger.

What the hell?

Dr. Müller? Sarah texted back. Where are you? And how do I know this is you?

After a moment, her phone beeped again. There was a photo of her own cover letter on Pols’s medical records. Then another message.

I can help your friend. Will you help me?

Sarah strode through the Naschmarkt, searching the stalls for a glimpse of Bettina. Had she not left town after all? Was she following Sarah? What game was this woman playing? Another message arrived.

There is something in the refrigerator of my apartment that must be returned. Use maximum discretion. No police.

Whatever was in the refrigerator, Sarah was guessing it wasn’t leftovers.

What is it? And who do I return it to?

But the return message read only: Paniglgasse 18. The concierge will let you in. Tell no one or I will not help you.

How do I know YOU WILL HELP ME? Sarah texted furiously. This wasn’t what she had imagined would happen in Vienna. This wasn’t how scientists operated. . . . This was as bad as fucking Prague!